Youth

Whoever thinks your future is more important than the weight of your past, then you are a youth.

If you think your possibility about your future is more important than the weight of your past, then you are youth. That is the definition of youth.

If you feel the weight of your past is too big than the possibility of your future, then you are already old.

References

http://nithyananda.org/video/ask-avatar-celebrate-guru-bhakti-through-sanyas#gsc.tab=0